CVE-2026-100659: Netty

Medium severity, CVSS 6.5. EPSS: 0.2% chance of exploitation in the next 30 days.

Netty's HTTP/3 codec (io.netty:netty-codec-http3) in versions 4.2.0.Final through 4.2.17.Final does not enforce the RFC 9114 requirement that the :authority pseudo-header field and a literal host header field, when both present, carry the same value. A remote unauthenticated peer can send a single HEADERS frame containing both fields with differing, attacker-controlled values; the request is accepted and delivered to the application with two conflicting authorities, allowing routing, virtual-host, and access-control decisions to be bypassed when different components in the request path consult different fields. This issue is fixed in 4.2.18.Final.

Affected products

• Netty Netty: from 4.2.0.Final, before 4.2.18.Final (fixed in 4.2.18.Final)

Published 2026-09-26. Last modified 2026-09-28.